Configurable multi-polar rf ablation probe

Abstract

A lesion control system includes a radio-frequency (RF) generator that produces RF energy having a predetermined frequency and power; a controller comprising a microprocessor; a multi-polar RF ablation probe having a plurality of electrical contacts; a plurality of RF input lines electrically coupled to an output terminal of the RF generator; a plurality of RF output lines, each RF output line electrically coupled to a respective one or more of the electrical contacts in the multi-polar RF ablation probe; an RF return line electrically coupled to a return terminal of the RF generator; and a plurality of switches, each switch having a respective terminal electrically coupled to a respective RF output line, each switch electrically coupled to the controller. The controller is configured to produce switch control signals that change a respective state of one or more of the switches to set a configuration of the multi-polar RF ablation probe.

What is claimed is: 
     
         1 . A lesion control system comprising:
 a radio-frequency (RF) generator that produces RF energy having a predetermined frequency and power;   a controller comprising a microprocessor;   a multi-polar RF ablation probe having a plurality of electrical contacts;   a plurality of RF input lines electrically coupled to an output terminal of the RF generator;   a plurality of RF output lines, each RF output line electrically coupled to a respective one or more of the electrical contacts in the multi-polar RF ablation probe;   an RF return line electrically coupled to a return terminal of the RF generator; and   a plurality of switches, each switch having a respective terminal electrically coupled to a respective RF output line, each switch electrically coupled to the controller,   wherein the controller is configured to produce switch control signals that change a respective state of one or more of the switches to set a configuration of the multi-polar RF ablation probe.   
     
     
         2 . The system of  claim 1 , wherein the controller is configured to produce first control signals that cause a first one or more of the switches to transition to an RF power-connected state in which the first one or more of the switches electrically couple one or more respective RF output lines to one or more respective RF input lines to form one or more respective positive contacts. 
     
     
         3 . The system of  claim 2 , wherein the controller is configured to produce second control signals that cause a second one or more of the switches to transition to an RF return-connected state in which the second one or more of the switches electrically couple one or more respective RF output lines to the RF return line to form one or more respective negative contacts. 
     
     
         4 . The system of  claim 3 , wherein the controller is configured to produce third control signals that cause a third one or more of the switches to transition to a disconnected state in which the third one or more of the switches is/are electrically decoupled from one or more respective RF input lines and from the RF return line to form one or more disconnected contacts. 
     
     
         5 . The system of  claim 1 , wherein:
 the switch control signals are first switch control signals, and   the controller is configured to produce second switch control signals during an RF ablation therapy to dynamically change the configuration of the multi-polar RF ablation probe.   
     
     
         6 . The system of  claim 1 , further comprising:
 a plurality of variable impedance matching circuits;   a plurality of impedance detectors, each impedance detector having an input electrically coupled to an output of a respective variable impedance matching circuit and an output electrically coupled to an input of the controller,   wherein each variable impedance matching circuit and each variable impedance matching circuit are electrically coupled to a respective RF input line.   
     
     
         7 . The system of  claim 6 , wherein:
 each impedance detector is configured to measure a respective measured impedance of the respective one or more of the electrical contacts and to send a respective output signal to the controller that represents the respective measured impedance of the respective one or more electrical contacts, and   the controller is configured to send respective impedance control signals to each variable impedance matching circuit to set an impedance of the respective RF output line based on the respective measured impedance.   
     
     
         8 . The system of  claim 7 , the respective impedance control signals cause each variable impedance matching circuit to match the impedance of the respective RF output line to the respective measured impedance. 
     
     
         9 . The system of  claim 7 , wherein the respective impedance control signals cause each variable impedance matching circuit to vary the impedance of the respective RF output line to balance a current flow to the electrical contacts. 
     
     
         10 . The system of  claim 7 , wherein the respective impedance control signals cause each variable impedance matching circuit to vary the impedance of the respective RF output line to unevenly flow current to the electrical contacts. 
     
     
         11 . The system of  claim 7 , wherein the controller is configured to produce a stop signal when the respective measured impedance is higher than a predetermined threshold impedance. 
     
     
         12 . A method for operating a multi-polar radio-frequency (RF) ablation probe, comprising:
 producing RF energy, with an RF generator, having a predetermined frequency and power;   directing the RF energy through a plurality of RF input lines that are electrically coupled to an output terminal of the RF generator;   with one or more first switches, selectively electrically coupling a respective one or more first electrical contacts in the multi-polar RF ablation probe to a respective RF input line to form one or more positive electrical contacts;   with one or more second switches, selectively electrically coupling a respective one or more second electrical contacts in the multi-polar RF ablation probe to an RF return line to form one or more negative electrical contacts, the RF return line electrically coupled to a return terminal of the RF generator; and   directing the RF energy from the one or more positive electrical contacts to the one or more negative electrical contacts to produce a therapeutic RF electric field.   
     
     
         13 . The method of  claim 12 , further comprising with one or more third switches, selectively electrically decoupling one or more third electrical contacts in the multi-polar RF ablation probe from the respective RF input line and from the RF return line to form one or more disconnected electrical contacts. 
     
     
         14 . The method of  claim 12 , further comprising while producing the therapeutic RF electric field, changing a state of a first one of the first switches from (a) an RF power-connected state in which the first one of the first switches electrically couples the respective one or more first electrical contacts to the respective RF input line to (b) an RF return-connected state in which the first one of the first switches electrically couples the respective one or more first electrical contacts to the RF return line, whereby a polarity of the respective one or more first electrical contacts is dynamically changed. 
     
     
         15 . The method of  claim 12 , further comprising producing, with a microprocess-based controller electrically coupled to the one or more first switches and to the one or more second switches, first and second switch control signals to set a state of the one or more first switches and a state of the one or more second switches. 
     
     
         16 . The method of  claim 12 , wherein:
 a respective variable impedance matching circuit and a respective impedance detector are electrically coupled to each RF input line, and   the method further comprises: 
 measuring an impedance, with the impedance detectors, of a respective first electrical contact(s) and of a respective second electrical contact(s); and 
 with a microprocess-based controller having an input electrically coupled to an output of each impedance detector to receive a respective measured impedance from each impedance detector, sending a respective impedance control signal to each variable impedance matching circuit to set an impedance of a respective RF output line based on the respective measured impedance, each RF output line electrically coupled to (a) a respective first switch and the respective one or more first electrical contacts or (b) a respective second switch and the respective one or more second electrical contacts. 
   
     
     
         17 . The method of  claim 16 , wherein the respective impedance control signal causes each variable impedance matching circuit to match the impedance of the respective RF output line to the impedance of the respective first electrical contact(s) or the respective second electrical contact(s) that is/are electrically coupled to the respective RF output line. 
     
     
         18 . The method of  claim 16 , wherein the respective impedance control signal causes each variable impedance matching circuit to vary the impedance of each respective RF output line to vary a current flow to the respective first and second electrical contacts. 
     
     
         19 . The system of  claim 16 , further comprising:
 monitoring, with the controller, the impedance of the respective first electrical contact(s) and the impedance of the respective second electrical contact(s) during an RF ablation therapy procedure; and   stopping, with the controller, the RF ablation therapy procedure when the impedance of any of the respective first electrical contact(s) or the impedance of any of the respective second electrical contact(s) is higher than a predetermined threshold impedance.   
     
     
         20 . A method for performing radio-frequency (RF) ablation therapy, comprising:
 inserting a multi-polar RF ablation probe into a subject, the multi-polar RF ablation probe including a plurality of electrical contacts;   selectively electrically coupling at least a first electrical contact in the RF ablation probe to a respective RF input line that is electrically coupled to an output terminal of an RF generator to form at least a positive electrical contact;   selectively electrically coupling at least a second electrical contact in the RF ablation probe to an RF return line that is electrically coupled to a return terminal of the RF generator to form at least a negative electrical contact;   producing RF energy with the RF generator to perform RF ablation therapy using the positive and negative electrical contacts; and   dynamically changing a configuration of the electrical contacts while performing the RF ablation therapy.